Sideways-related, but I was just commenting on Erich von Stroheim's classic Greed film. It was originally like 9hrs, but only 2hrs were rescued, at thought presumed to exist for many decades.
Later, in the early aughts (2000's), a bunch of images and clips were found, leading to the creation of a restored 4hr version.
Comment and links here:
https://piefed.social/post/1983335#comment_10963552